The long term objective of this research proposal is to develop and expand field-flow fractionation (FFF) technology in such a way that its intrinsic advantages can be readily realized and applied to complex biochemical materials. Another objective is to push back the frontiers of separation methodology. The above objectives are to be met by pursuing work in four categories: 1. General Optimization of FFF. Here we weill seek improvements in instrumentation, channel design, and procedures in order to make FFF more accessible and more useful to the broad scientific community. As part of this study, we will examine the optimization of programmed FFF. 2. Biochemical Applications. We will engage in several projects of direct biochemical relevance, working mainly with collaborators from the biomedical community. 3. Two-Dimensional FFF. We will undertake a major long-term initiative to combine the high resolving power and versatility of two-dimensional methodology with the advantage displayed by FFF in the separation of macromolecular and particulate components. In this way we hope to evolve new and powerful separation techniques. 4. Developments in Separation Science. Here we will continue our long-standing efforts to broadly advance the theoretical understanding of basic separation processes. In addition, we will seek to develop new separation approaches and techniques.